Multitubular boiler



United States Patent lnve ntor Le'on Jacques Wanson 118 Avenue lsidore Gheyskens, Auderghem, Belgium Appl. No. 819,054 Filed April 24, 1969 Patented Sept. 22, I970 MULTITUBULAR BOILER 1 Claim, 2 Drawing Figs.

US. Cl 122/248 int. Cl F22b 21/28 Field of Search l22/ 247,

[56] References Cited UNITED STATES PATENTS 1,970,747 8/1934 Hamm et al. V l22/248X 2,645,210 7/1953 Harris et al. 122/248 Primary Examiner-Kenneth W. Sprague Attorney-Young and Thompson ABSTRACT: A multitubular boiler including several layers of coiled tubes wherein two adjacent coils pertain to two different tubes in the same layer is provided with a double jacket wherein at least a fraction of the air admitted to the burner is circulated for preheating it.

MULTITUBULAR BOILER FIELD OF THE INVENTION The present invention relates to a multitubular boiler for a heat transfer fluid designed to be used with a circulation loop feeding heat exchanging apparatuses.

BACKGROUND OF THE INVENTION Boilers provided with a double-jacket wherein at least a fraction of the air admitted to the burner is circulated for preheating it are well known. Multitubular boilers provided with several layers of coiled tubes wherein two adjacent coils pertain to two different tubes in the same layer are also known.

SUMMARY OF THE INVENTION The object of the invention is a boiler combining the advantages of the boilers of said both types, with none of the drawbacks thereof. The invention consists in arranging a coil system identical to that of a boiler of the second type in a jacket-system similar to that of a boiler of the first type. It has been found that a very compact boiler is obtained in this way, which, notwithstanding its small dimensions, yields a great calorific power that is higher than that which could theoretically be anticipated by merely adding together the particulars of the boilers of said both types. It is believed that the novel effect obtained by the inventive apparatus results from the relative arrangement of the different circuits.

DRAWING In the appended drawing:

FIG. 1 shows a longitudinal section of a boiler according to the present invention.

FIG. 2 shows a detail of the boiler of FIG. 1, taken along arrow P on FIG. 1.

The boiler according to the present invention comprises a plurality (illustratively three) of layers 100, 200, 300, each including a number of concentric coiled tubes. The internal layer defines the peripheral wall of a fire box 10 provided with a central burner 25. The adjacent successive coils 1, 2, 3, 4 of the external layer 100 are connected to a distributor 5--as shown as 6, 7, 8, 9. The next following coils l, 2, 3', 4 are connectcdto the preceding ones in the same order, coil 1 being continued by coil 1', coil 2 beingcontinued by coil 2 and soon. The general flowing direction is from the left to the right as viewed on FIG. 1 in the layer 100, then from the right to the left in layer 200 and from the left to the right in the layer 300. The fluid is discharged from the coils placed at the right end of layer 300 by means of tubes such as 301 provided with individual flow-rate controlling devices (not shown).

Layer 100, which is fed with cold fluid through distributor 5 is surrounded by a first sheet jacket 23. A second jacket 22 surrounds thejacket 23 with a first annular space 320 between them. A third jacket 21 surrounds jacket 22 with a second annular space between them. These annular spaces 320 and 120 are closed by means of a common wall 132 at their end adjacent to the distributor 5. An annular fume box 13 is connected to a stack 14. Fume tubes 12, connected to fire box 10 by the end of the tubes located on the burner side, extend through space 320 and are connected to the fume box 13. The latter is enclosed as a whole in the external jacket 21. The end of space 320, on the burner side, is connected through an annular space 15 to an air inlet chamber 17. This chamber is fed by the fan 16 through chamber 26 and passages 18. Other passages 19, the aperture of which is ad ustable through axial displacement of an annular register 27 are connected with a chamber 24 surrounding externally the annular chamber 15 and that is connected to the annular space 120 on the burner side of the boiler. The air fed by the fan 16 passes from chamber 26 to chamber 24 along arrows f4 while being preheated. It passes around the fume box 13 and flows along arrows f5 into chamber 15 and hence it reaches the burner along arrows f6. The temperature of the air increases gradually as it progresses along the fume tubes 12, which are circulating hot fumes in the opposite direction.

Iclaim:

1. Boiler for heat transfer fluid comprising a plurality of similarly shaped tube means circulating a heat transfer fluid, arranged in several coaxially extending layers, each layer being comprised of a number of successive sets of adjacent coils wound such that at least two adjacent coils in each set pertain to two different ones of said tube means, the most internal of said layers defining a cylindrical fire box having first and second ends, a central burner means adjacent to said first end of said fire box and having at least one inlet for combustion-supporting air, a first end wall for said fire box at said second end thereof, a first jacket means surrounding the most external of said layers, a second jacket means extending coaxially to said first jacket means and surrounding same in a spaced apart relationship to form between said first and second jacket means a first annular chamber, a third jacket means extending coaxially to said first and second jacket means and surrounding said second jacket means in a spaced apart relationship to form between said second and third jacket means a second annular chamber, a second end wall for said first and second annular chambers at said second end of said fire box, a fume box means near said second end of said fire box and adapted to be connected to a stack, a plurality of fume tube means having a first end thereof adjacent to said first end of said fire box and communicating with same, extending longitudinally to said first annular chamber and having a second end thereof connected to said fume box means, a passage between said first and second annular chamber adjacent to said second end of said fire box, a third chamber adjacent to said first end of said fire box and coupling said first annular chamber to said air inlet to said burner means, and means to intake air under pressure into said second annular chamber on the side of said fire box, which is adjacent to said first end thereof, distributor means for said heat transfer fluid adjacent to said second end of said fire box and independently connected to the first set of adjacent coils of said most external layer. 

